Syllabus Coverage: NFC3.1
The back end of the nuclear fuel cycle covers everything that happens to the fuel after it has been irradiated in the reactor. This includes:
- Removal of irradiated fuel from the reactor core
- Short-term storage of irradiated fuel on-site (cooling)
- Transport of the fuel off-site
- Reprocessing (if the once-through cycle is not adopted)
- Long-term disposal of unrecycled fuel or reprocessing waste
Each stage presents significant health physics challenges because the fuel contains extremely high levels of radioactive fission products and actinides. Two key points drive all back-end operations:
- Decay heat from fission products means the fuel must be continuously cooled, even after the reactor is shut down.
- Mobile fission products (gases and volatiles) constitute the major off-site hazard in the event of an accident.
Key Terminology: The term “irradiated fuel” is used in preference to “spent fuel” throughout this chapter, because the fuel still contains over 90% of its original fissile content after discharge from the reactor.